ATX Power Supply - the elegant way to adapt to benchtop use...

 If you want to use an ATX power supply as a benchtop unit, without hacking it to pieces or risking fire and electrocution, then this approach is definitely for you. 

NEWS: due to increasing inquiries I have made this item in to a complete kit. Let me know if you or your college / lab are interested. Full schematics BOM and assembly docs are provided too. 

Step 1: Acquire the ATX PSU Benchtop Adapter PCB

 This PCB has been specifically designed for this purpose, and is layed out for access to all the ATX supply votlage rails, even the standby supply and the "power good" signal. This PCB can be acquired from http://www.jordandsp.com/index.php?p=1_2_Projects. Since there was enough interest in using it, I had quite a few manufactured to get the price down.

Comments

[OmegaRa]

I wish I had seen this BEFORE I cut all the wires in my spare PSU...lol...well I can try the other way and if it fries...PSU's are cheap lol.

[e5frog]

Nice little build.
Does anyone know if there's a box that fits the construction, I'd hate to accidentally short something because of the exposed metal, accidentally nudging it into the PSU for example.

[Legoman132]

I got mine and put it together yesterday, and it works MUCH better than just shoving wires in the connectors. However, when I reinforced the 12 and 5v traces with solder (those are what I plan on using heavily), there was a tiny error in the solder mask exposing a sliver of ground plane next to the 12v line. This shut my ATX down initially, but I eventually removed enough solder to where the current blew the short out with a nice pop, after which it worked perfectly. Has anyone else had this happen?

[jordanyte]

Thanks for the comment!

I have noticed since you mentioned it that the mask registration is not perfect on a few of the boards I had made. I'll feed this information back to the fabricator and hopefully the next batch will be of a higher standard.

[brusho150]

HI!
I am new in electronic engineering and wanted a lab power supply will you please tell me that how Can we add a potetiometer(voltage regulator),rheostat, voltmeter and ammeter to calculate and vary voltage and current?
Thanks

[darthneo]

Can i ask where you got the banana posts?

They seem quite expensive on electronics websites (digikey, mouser, jameco)
Ebay has 5 (5 different colors) for 5.30$, i wouldn't expect these to be so expensive...

[jordanyte]

I have solved the banana post problem. Yes you are right in small quantities banana posts are quite expensive.

So... after getting lots of PCBs made, I also went ahead and bought enough parts - banana posts included, (the color coded ones as shown) - to populate them all.

So now I can provide a complete kit for you. This kit with the board and all the parts is cheaper than if you went to Jameco or others and bought them all.

[darthneo]

Oh, thats cool! i have put all my electronic projects on hold because of college and work, but i ended up getting, i think, 12 banana posts for 10$ off ebay.

Out of curiosity how much are you selling the complete kit for?

[jordanyte]

I have put together complete kits for $30USD plus shipping. I will offer discounts for bulk orders (i.e. school labs).

[1clicc]

I went to your website but there's no where to order one. Can you point me to the right direction to where i can acquire one? Thanks.

[jordanyte]

Please contact me through the inquiry form and I'll get you the details. Or you could email me direct - ben#jordandsp%com where # = @ and % = . (please forgive the necessary anti-spam obfuscation)

[darthneo]

I think you just send him $20 through paypal and he sends you one

[merlinmalone]

Nice little project. As an electronic engineer I was planning to do the same, then came across your design. A couple of questions:

1. What are the outputs rated at (without adding solder to the traces)?
2. Do you have problems with the nuts on the posts shorting out between the copper planes on the PCB? In the pictures on your website they seem to overlap in places - maybe if you do another version increase the space around the terminals.

As a suggestion, rather than putting it in a box it might be nice just to have a sheet metal 'L' shape made up which you can bolt both your board and the ATX supply to - it doesn't really matter that it's open and makes it a neat unit.

Also, not sure that adding vias around the holes "offer increased strength for tightening up screws over" - removing material decreases strength, but it looks nice :)

[jordanyte]

1. The 5V rail would easily handle 40+ amps. The others a similar however the -12V rail had narrower traces, simply because a typical ATX supply cannot provide more than a few amps on that rail. I would say the PCB can handle more current there than most supplies could give.

2. The post mounts are specifically designed for the binding posts used. I have these available in a kit form. You *might* be able to use other posts but the ones I specified in the design will NEVER have ANY problems shorting to ANYTHING.

As you say, it would be nice to mount the PCB directly on a bracket on the benchtop. Well, if you look closely at the alligator clip slots I included - this makes perfect sense and is in fact just how it's intended to be used. But there's no reason not to put it in a box if you would prefer either _ I just wanted it to be flexible. Great minds think alike :-)

As for the vias - well, the *real* reason they are there is to lower the connection impedance to the binding posts - not that it would make a huge difference, but it feels good having them there ;-)

Thanks for checking it out!

[merlinmalone]

I don't think you'd want to draw 40A on the 12V (down two wires) - you might release the 'brown' smell. :)

Looking at the image on your site: http://www.jordandsp.com/images/board_and_multimeter.jpg the nut under the yellow terminal in particular looks like it overlaps the plane gap. Maybe the chamfer on the nut is enough to clear it though.

I personally probably wouldn't use the croc clip points (nice feature for many though) and would mount the board on the back of a metal panel using the terminals. Depending on the length of terminal you use you should be able to clear the components on the board, maybe need some stand-offs on the mounting holes..

A good source for the 4mm terminals is Farnell if you have one in your country. Links to the relevant UK parts: http://uk.farnell.com/jsp/search/results.jsp?N=1011020+401&Ns=PRICE_PLS_006_PRICE1|0

[jordanyte]

Definitely.

The binding posts shown in the images have insulated nut/washer on the front side of the board, so if you are mounting on a panel the binding posts will probably be all you need for a secure mounting (after all there are ten of them :-))

Also, these posts when mounted allow all the other components to clear the panel. When I did the PCB design I did a full 3D mechanical model also to make sure this would work.

The other good thing another person pointed out is that you also have the solder pins available behind the posts on the rear side - which he intended to use to solder on a 20W "minimum load" resistor (though all the supplies I have used with it did not require a minimum load - they regulated well just with the internal fan - but not all PSUs can do that, particularly older ones).

[merlinmalone]

Also, to increase the current capacity of the +12V rail (as it's only 2 pins on the ATX connector) you could add sockets for one or more of the disk drive connectors.

[alfa2red]

You done some thinks nice. But if all the part was installed inside like the first project has done years ago it look better.

[Chestum]

great work, looks great. sent ya an e-mail ( Curtis )

[jordanyte]

Hi Everyone, Since the first short run all found new homes, and I am still getting inquiries about the board, I have taken the plunge and had a large batch of them made. There are three of major benefits - 1) I was able to implement some minor changes and improve the function of the board. Particularly the ATX connectors available at low-cost from Jameco (or the more expensive Molex ones from DigiKey) which are 20-pin connectors, fit perfectly with an updated PCB footprint. 2) The switching functions have been labelled in the silkscreen, and I also made the main on-off LED indicator bi-color: green for Standby and red for On. The other LED is the "no-Power Good" indicator so flashes on at the beginning and goes off when the rails have settled. If it stays on it means the PSU has a fault. 3) They are a lot cheaper to make because I made a lot of the new boards. Let me know if you want one or two (or a bunch for a university lab) and I'll send you the details. I chose not to swap the connector location with the mounting holes as the intent was always to mount the board on angle brackets hanging from a shelf above my workbench, or mounted from a front-panel of an enclosure. I also decided to go for an electroless gold finish (harder to solder, but better for the environment etc. etc. and besides, it just looks better ;-) ), and black solder mask. See the updated image. Also, I'll soon post a short youtube video showing how it functions - stay tuned.

[The Ideanator]

This is a lovely idea, but for $20, I'd want a nice little acrylic case that can be attached to the psu box with minimal effort (some drilling isnt bad)
Here's a suggestion for revision 2, on the connector side of the board, flip where the holes and connectors are so one could easily mount it on the psu with standoffs (that you might throw in to a kit)

[jordanyte]

Thanks for the feedback!

[frollard]

That's really cool!  How would you feel about open sourcing the schematic for the DIY among us?

[The Ideanator]

Don't forget the pcb images.

[jordanyte]

 Hi All who are interested:

I have put the schematics and assembly drawing at the following location:
www.jordandsp.com/web_images/atx_psu_adapter.pdf 

This design is simple - anyone could have done it. Even so, it's (C) copyrighted ownership of Benjamin Jordan.

Feel free to make your own, but don't copy it and pass it off as your design. Please give credit where it's due.

And, for those who are interested I have a few PCBs still, and will make more if more people want one. Please email me ben [at] jordandsp [dot] com if you would like one.

[frollard]

Oop:  double post...

How does this circuit deal with the required load on the 5v line?  My understanding is the supply will start cooking itself if it doesnt have any load to regulate for.

[jordanyte]

Hi frollard,

I do know some older SMPS (i.e. pre-ATX standard era) were not able to run without a load. I have tested numerous ATX ones and all of those were okay without it (the fan was enough of a load). I guess there's nothing to stop you adding a load to this via therminals though.

I will post PDFs of the schematic soon - I'm not on the right PC at the moment.... but they're seriously nothing complex. Anyone could do this if they were so inclined.

BTW I do have a few boards made. If enough folks are interested I'll do another batch.